Process timers



R. J. CARTlER PROCESS TIMERS Feb. 28, 1967 3 Sheets-Sheet 1 Filed Aug. 26, 1964 INVENTOE Fae/:72 JfGwzr/z/e ATTORNEY.

R. J. CARTIER PROCESS TIMERS Feb. 28, 1967 5 Sheets-Sheet 2 Filed Aug. 26, 1964 w n: M

ATTORNEY United States Patent 35%,118 PRSCESS TIMER-RS Roger John Cartier, Vimercate, Milan, Italy, assigns: to Controls Company of America, Melrose Park, 111., a corporation of Delaware Filed Aug. 26, 1964, Ser. No. 392,196 Claims priority, application Great Britain, Sept. 7, 1963, 35,418/63 Claims. (Cl. 74150) This invention relates to stepping mechanisms and to process timers incorporating such mechanisms. More particularly the invention relates to a timing mechanism of the intermittent or step-by-step type incorporating a stepping mechanism and designed for use in controlling the functions of a washing machine.

According to the present invention there is provided a stepping mechanism comprising a ratchet, a pawl biased for engagement with the teeth of said ratchet, means for reciprocating the pawl and operable in each reciprocation to advance the ratchet through a step of one tooth, and means for preventing engagement of the pawl with the ratchet for a predetermined period of time.

More particularly the present invention provides a stepping mechanism comprising a ratchet wheel, a pawl biased for engagement with the teeth of the ratchet wheel, means for reciprocating the pawl and operable at each reciprocation to advance the ratchet wheel through a step of one tooth, a ratchet-toothed member mounted for translational movement transverse to the axis of the ratchet wheel into and out of an active position in which it engages said pawl and disengages the pawl from the ratchet wheel, said member having a plurality of ratchet teeth disposed along a line substantially parallel to the periphery of the ratchet wheel, the ratchet-toothed member also being mounted for pivotal movement about the axis of the ratchet wheel so that, when said member is in its active position, each reciprocation of the pawl effects a pivotal displacement of said member through a step of one tooth, and including control means for controlling the translational movement of the ratchet-toothed member toward the pawl, and operative in response to a predetermined pivotal displacement of the ratchet-toothed member to release said member from engagement with the pawl.

The manner in which such a stepping mechanism can usefully be supplied to an interval timer will now be explained.

One form of such interval timer, comprises a bank of rotary cams which are rotated in a step-by-step manner at intervals, and at each interval the cams selectively actuate switches for controlling the washing machine functions. The drive of such an interval timer conveniently comprises a single synchronous motor having a fixed speed and which acts through a stepping mechanism to rotate the cam bank intermittently. Such a stepping mechanism conveniently comprises a ratchet mechanism having a spring in which potential energy is stored until the mechanism is tripped by a cam rotated continuously by the motor, and the cam bank is rotated through one step. I

If now, for example, the motor output shaft rotates at one rpm. and the cam bank steps each time the motor output shaft rotates through one revolution, the interval between steps is of one minute duration. Process functions taking longer than one minute therefore require more than one interval for their completion, for example a four minute function will require four intervals.

The advances in modern textile fibre research have resulted in increasing numbers of new textile materials being made available with varying laundering requirements. These in turn have made it necessary to provide domestic machine timers having ever increasing flexibility of operation to permit the required variety of washing programmes to be performed. Multi-programme washing machine timers require a very large number of intervals to handle these programmes, but production problems limit the numbers of intervals which a conventional timer can handle in 360 of rotation.

Thus by incorporating a stepping mechanism, in accordance with the present invention, in an interval timer of the type described above, a high degree of flexibility can be achieved since if the ratchet-toothed device has, for example, four ratchet teeth, the interval during which the device is active will be extended by four times its normal duration.

The present invention therefore, according to another aspect, comprises a timing mechanism of the type having control cams mounted for step-by-step advancement by means of a reciprocating pawl engaging a ratchet wheel rotatable with the cams, a masking device selectively movable into a position in which it holds the pawl from engagement with the wheel, and means on the masking device engageable by the pawl to permit the pawl to move the masking device out of its masking position.

One embodiment of stepping mechanism in accordance with the present invention will now be particularly described with reference to the accompanying drawings in which:

FIG. 1 is a section through a process timer, taken on the line II of FIG. 4 and showing the basic parts of the stepping mechanism;

FIG. 2 is a section on the line 11-11 of FIG. 4 showing the parts of the mechanism which are operable to extend the time duration of an interval, the parts being illustrated in their-active position;

FIG. 3 is a view corresponding to that of FIG. 2 but showing the parts in their inactive position; and

FIG. 4 is a side elevation, part sectioned, of the timer.

As shown in the drawings, the timer comprises a cam bank 10 (FIG. 4) which is mounted for rotation coaxial with a ratchet Wheel 11 through which the cam bank is driven. A drive pawl 12, which is biased into engages ment with the teeth of the ratchet wheel by a spring 13, is pivoted on one end of a cranked drive lever 14 which is pivotally supported at 15 on the timer frame 16, the

opposite end of the drive lever being urged by a spring- 17 into contact with a cam 20 rotatable through gears 18, 19 from the output shaft 21 of the timer motor 22;

This cam 20 is of the slow-rise fast-drop type so that at each revolution of the cam, the drive lever 14 is pivoted against the force of its spring to move the drive pawl 12 over one of the teeth 11a of the stationary ratchet wheel 11, and when the cam drop is reached, the quick reverse movement of drive lever under the influence of the spring 17 causes the drive pawl to rotate the ratchet wheel through one step ie the pitch of one tooth. To prevent the ratchet wheel firorn being dragged backwards as the drive pawl is moved slowly back across a tooth, a locating lever 23 is urged by a spring 24 into engagement with the teeth of the ratchet wheel. 7 I

In order to increase in effect the length of an interval,

a mechanism is provided to permit the drive pawl to op-- erate at least twice and preferably several times without advancing the ratchet wheel through a step, by trans ferring its action away from the ratchet wheel.

This mechanism, in the illustrated embodiment, consists of an actuator comprising an elongated plate shaped actuator member or masking device 26 mounted in a plane parallel to that of the ratchet wheel and having therein an elongate hole 26a through which extends a stud shaft 27 projecting from the centre of the ratchet wheel 11. Across one end of the actuator plate is a row of ratchet teeth 26b for example four such teeth, matching those of the ratchet wheel and disposed along an arc of substantially equal curvature. The drive pawl 12 is made broad enough to engage either the teeth of the actuator plate or the teeth of the ratchet wheel according to whichever are at the greater radial distance from the shaft 27. The hole 26a in the actuator plate is sufficiently long to permit the plate to be moved radially either in a direction towards the pawl into an active or masking position in which its teeth are raised above those of the ratchet wheel and thereby raise the drive pawl out of engagement with the ratchet wheel, or in the opposite direction to disengage the actuator teeth from the drive pawl. The width of the hole is such as to prevent lateral movement of the actuator plate on the shaft 27.

The means for controlling the position of the actuator plate comprise an actuator lever having an arm 30 which is connected by a pivot 31 at one end to the timer frame and carries a cam follower 32 which rides on the periphery of the first cam 33 of the cam bank, i.e. the cam next adjacent the ratchet wheel. The opposite end of the actuator lever is pivoted to the outer end of one arm 34a of an L shaped trip member 34 which is biased by a spring 35 to hold the cam follower 32 against the cam 33, and is guided in a slot 36 in the frame 16 for movement substantially parallel to the length of the actuator plate.

The other arm 34b of the trip member supports a row of positioning teeth 34c of undulating shape, corresponding in number to the number of ratchet teeth on the plate, and the positioning teeth of the trip member mesh with a corresponding row of similarly shaped positioning teeth 260 which extend across the end of the actuator plate remote from its ratchet teeth. A spring 37 acts on the actuator plate 26 obliquely to its length to bias it in a radial direction away from the pawl and also to rotate it into a position in which a projection 26a at one corner of the plate adjacent the endof the row of its positioning teeth abuts a ganist the end of the adjacent arm 34b of the trip member. Alternatively two separate springs could be used to effect the translational and' rotational movements respectively of the actuator plate. In this position illustrated in FIG. 2, the two rows of positioning teeth are fully in mesh and, at the opposite end of the actuator plate, the drive pawl, having completed a backward movement, lies in the trough between the first two actuator ratchet teeth.

Assume however that the cam 33 controlling the actuator has just caused the actuator plate 26 to be displaced radially from a starting position to raise its ratchet teeth 2611 until they lie above the teeth 11a of the ratchet wheel, and the drive pawl 12, at the beginning of its rearward movement is engaging over the first ratchet tooth of the actuator plate. Then upon the completion of the rearward movement of the drive pawl, it engages as illustrated behind this tooth and, upon advancing, the actuator plate is rotated through a step of one tooth. At the same time the positioning teeth are displaced through one tooth distance relative to each other against the force of the plate-biasing spring 37 to hold the actuator plate in its displaced position. However the ratchet wheel and in consequence the cam bank are unaffected and remain stationary. This is repeated at the next two operations of the drive pawl. At the fourth operation of the drive pawl, the positioning teeth 26c of the actuator plate become disengaged from the corresponding teeth 340 of the trip member and the spring 37 biasing the actuator plate moves it radially away from the drive pawl into an inactive position in which the actuator teeth lie below those of the ratchet wheel and the drive pawl once again engages the ratchet wheel. The actuator plate is retained in its inactive position by engagement of one side of the plate with the end of the adjacent arm 34b of the trip 34 as shown in FIG. 3, and will remain in this starting position prior to acting once again in removing the drive pawl from the ratchet wheel. The resetting of the actuator plate is effected automatically in response to the cam follower 32 of the actuator lever dropping into a recess in the first cam 33 of the cam bank. This allows the trip member 34 to be moved under the force of its biasing spring 35 to pull the end of the trip member arm 34b away from the actuator plate allowing the latter to swing back until the projection 26d of the plate once again abuts against the end of the trip member arm 34b.

It will be evident that the number of ratchet teeth on the actuator (and the equal number of positioning teeth on the actuator and trip member) determine the number of steps in each extended interval. Moreover the shape of the first cam will determine the number of intervals, and the position of the intervals, which will be extended intervals. In the limiting case, each interval could be made an extended interval.

By provision of a suitable discriminating system, the number of actuator ratchet teeth which are operative can be varied thereby to vary the length of any extended interval.

Although only one embodiment of the invention has been described in detail, it will be evident that numerous variations could be made Within the scope of the present invention. For example means equivalent to, but different from, the positioning teeth and trip member could perform the same function of moving the actuator ratchet teeth into and out of operation. Moreover the actuator could be put into and out of action by means other than a cam of the cam bank. In this way, resetting of the actuator could 'be effected after any selected number of operations of the pawl and the length of the extended interval could therefore be selected at will.

I claim:

1. In a timing mechanism having control cams mounted for step by-step advancement by means of a reciprocating pawl engaging a ratchet wheel rotatable with the earns, the improvement which comprises a masking device,

trip means actuated by one of the control cams for selectively moving said masking device into a position in which it holds the pawl from engagement with the wheel, and

means on the masking device engaged by the pawl to permit the pawl to move the masking device out of its masking position.

2. A mechanism according to claim 1 wherein said masking device has a plurality of ratchet teeth for engagement with said pawl and wherein said pawl is operative at each reciprocation to displace said masking device through a step of one tooth, said trip means being operative after a predetermined displacement of the masking device to release it from engagement with said pawl.

3. A mechanism according to claim 2 including biasing means acting on said masking device in a sense to withdraw it from said pawl, the displacement of the masking device under the action of the pawl effecting relative displacement between the masking device and the trip means until a position is reached in which the masking device becomes disengaged from said trip means.

4. A mechanism according to claim 3 including means mounting said masking device for translational movement into and out of engagement with the pawl and for pivotal movement under the reciprocating action of said pawl.

5. A mechanism according to claim 4 wherein said trip means and said :masking device are both formed with undulations which, when the masking device is in its masking position, mutually engage to resist pivotal dismember position until it is reset to 1ts placement of the masking device, but which are moved relatively away from each other at each step of the masking device.

6. A mechanism according to claim 5 wherein said trip means is movea'ble away from said masking device to release the latter and permit it to return to its starting position under the force of said biasing means.

7. A mechanism according to claim 6 wherein said trip means is connected to said one of said control cams by a pivoted arm, means mounting the trip means for substantially rectilinear movement, biasing means acting on the trip means in a sense to move it in one direction, said one of said control cams acting on said arms to cause the trip member to move in the opposite direction.

8. A mechanism according to claim 7 wherein said control cams are rotatable with the ratchet Wheel.

9. A timing mechanism comprising a ratchet wheel,

a pawl biased for engagement with the teeth of the ratchet wheel,

means for reciprocating the pawl and operable at each reciprocation to advance the ratchet wheel through a step of one tooth,

a ratchet-toothed masking member mounted for translational movement transverse to the axis of the ratchet wheel into and out of a masking position in which it engages said pawl and disengages the pawl from the ratchet wheel, said member having a plurality of ratchet teeth disposed along a line substantially parallel to the periphery of the ratchet wheel, the ratchet-toothed member also being mounted for pivotal movement about the axis of the ratchet Wheel so that, when said member is in its masking position, each reciprocation of the pawl effects a pivotal displacement of said member through a step of one tooth, and including control means for controlling the translational movement of the ratchet-toothed member toward the pawl, and means operative in response to a predetermined pivotal displacement of the ratchet-toothed member to release said member from engagement with said pawl.

10. A mechanism according to claim 9 wherein said control means act in response to rotation of the ratchet wheel.

References Cited by the Examiner UNITED STATES PATENTS FRED C. MATTERN, JR., Primary Examiner. F. E. BAKER, Assistant Examiner. 

1. IN A TIMING MECHANISM HAVING CONTROL CAMS MOUNTED FOR STEP-BY-STEP ADVANCEMENT BY MEANS OF A RECIPROCATING PAWL ENGAGING A RATCHET WHEEL ROTATABLE WITH THE CAMS, THE IMPROVEMENT WHICH COMPRISES A MASKING DEVICE, TRIP MEANS ACTUATED BY ONE OF THE CONTROL CAMS FOR SELECTIVELY MOVING SAID MASKING DEVICE INTO A POSITION IN WHICH IT HOLDS THE PAWL FROM ENGAGEMENT WITH THE WHEEL, AND MEANS ON THE MASKING DEVICE ENGAGED BY THE PAWL TO PERMIT THE PAWL TO MOVE THE MASKING DEVICE OUT OF ITS MASKING POSITION. 